Functional particles may be incorporated into a fibrous structure for a variety of reasons. For example, filter media or fibrous filters may include sorptive particles for selectively removing certain components of a liquid or gas passing through the filter. Alternatively, functional particles may release an active or desirable agent into a fluid stream. Furthermore, functional particles may be chemically or catalytically or otherwise reactive with or attractive to a fluid stream constituent. In any event, the functional particles need to be accessible. Accessibility is benefitted when the particles are distributed in a three dimensionally spaced apart arrangement.
Especially useful functional particle-containing fibrous structures are exemplified by U.S. Pat. No. 3,971,373 to Braun, and U.S. Pat. Nos. 5,605,746 and 5,674,339, both to Groeger et al, and are characterized by immobilized functional particles three dimensionally distributed and entrapped in a fibrous matrix, and beneficially bonded to the fibrous matrix. Conveniently, these fibrous structures are made in the form of a continuous web. However, when the continuous web is cut into sections or pieces, the immobilizing fibrous structure in the area of the cutting is disturbed with a result so that functional particles in the area are exposed and could be released from the fibrous structure.
In many applications, release of functional particles from a containing fibrous structure is of no significant consequence. However, sorptive applications and other applications do exist for which it is beneficial or essential that functional particle release from a functional particle-bearing fibrous structure be minimized or even be eliminated.
Therefore despite advances in this art, there is needed a fibrous web loaded with functional particles, which when cut, does not release functional particles from the cut edges. Furthermore, it would be beneficial if the containing fibrous web did not allow release of the functional particles from locations which would not be disturbed by the cutting, even if functional particles are not immobilized.